Wjhat is the first step in allopatric speciation?

The first step in allopatric speciation is "geographic isolation".

Explanation:

Allopatric speciation happens when a population is geographically separated therefore also termed as "geographical isolation", it is also the very first step. In the laboratory, for instance, an isthmus that divides an ocean or fruit flies. The cultures on both ends of the barrier can not then balance one another, so each population develops independently.

Different geographical fluctuations may occur, such as continent movement and the creation of mountains, islands, water bodies, or glaciers. Human activity such as farming or growth can also alter the allocation of population groups of species.